This invention relates to electrical connecting devices, and in particular to an electrical offset adapter plug which may be inserted into the receptacle of an automotive cigarette-lighter assembly so that various low-voltage loads may be operated by the electrical system of the vehicle. An offset adapter-plug design is disclosed which facilitates insertion of an adapter plug into a receptacle having restricted access because the receptacle is housed in an ash tray compartment, for example.
In recent years, a great variety of electrical appliances have become available for operation by the low-voltage, direct-current power of the electrical systems of cars, power boats, and campers. These appliances are generally interconnected to the electrical system of the vehicle by use of an adapter plug or connector which is inserted into the cigarette-lighter socket or receptacle. Electrical appliances and accessories which can be operated from a vehicle electrical system vary widely and include portable television sets, tape recorders, trouble lights, window defrosters, electrical shavers, electric toothbrushes, can openers, food mixers, and the like.
Such prior art devices useful for electrical connection with cigarette-lighter receptacles include Focosi U.S. Pat. No. 2,954,544, Schwartz U.S. Pat. No. 3,099,505, Busch et al U.S. Pat. No. 3,377,610 and Busch U.S. Pat. No. 3,865,463.
In many instances, the variety and complexity of equipments operable from a vehicle electrical system require conversion of the vehicle voltage to a different selectable output value, or alternatively dual power outputs are required to operate plural units.
It is convenient to house the necessary voltage-conversion circuitry or dual-output receptacles inside the adapter-plug housing. But such association of necessity enlarges substantially the adapter-plug housing dimensions both in length and in width.
Vehicle manufacturers have in recent years removed cigarette-lighter receptacles from an exposed access mounting on the vehicle dash and control panels, and have instead concealed these receptacles within ash-tray compartments or in other difficult-to-access areas. As a result, many prior-art adapter plugs are too large or improperly dimensioned for easy insertion into receptacles having a restricted access. This particular situation exists in those instances in which auxiliary electrical components are incorporated into an adapter plug housing.